FR3085239A1 - SYSTEM FOR DETECTING A LOWER VOLTAGE OF AN ALTERNATIVE POWER SUPPLY - Google Patents

Abstract

The invention relates to a device (100) for detecting a voltage drop in an AC power supply (110) delivering electrical energy to an energy converter (130) in order to power electrical equipment (140a, 140b, 140c), the device (100) being connected to a reserve of electrical energy (120) for supplying the energy converter. The device (100) comprises: - a full-wave rectifier for rectifying the alternating supply, - a comparator which compares a first predetermined voltage with a full-wave rectified voltage, - a capacitor charging circuit for charging the capacitor when the rectified voltage is less than the predetermined threshold, - a capacitor discharge circuit for discharging the capacitor when the rectified voltage is greater than the predetermined threshold, - a comparator to compare the voltage across the capacitor with a second predetermined voltage, - a circuit control of the reserve of electrical energy.

Description

Description

Title of the invention: System for detecting a voltage drop in an AC supply

Technical Field [0001] The present invention relates to a system for detecting a drop in voltage of an alternative supply supplying electrical energy to an energy converter in order to supply electrical equipment.

PRIOR ART [0002] Electrical equipment, such as for example equipment on board an aircraft, is supplied by an energy converter which receives electrical energy via an electrical supply bus.

The energy converter modifies the value of the alternating supply voltage or rectifies the power supply voltage and modifies the value of the voltage to provide a supply of electrical energy suitable for electrical equipment.

When the power supply is interrupted or its amplitude is less than an operating threshold of the energy converter, the electric energy converter can no longer supply a supply of electric energy suitable for electrical equipment.

Energy reserves are associated with the energy converter to remedy this deficiency in the power supply and are controlled by a device for detecting a drop in voltage of the power supply.

These energy reserves depend on the equipment to be supplied and the period during which the latter must remain energized.

When the power supply is a continuous power supply (in English Direct Current DC), it is easy to detect a total loss of the power supply or a decrease in the amplitude thereof. A simple comparison of this with a threshold is sufficient and makes it possible to quickly order an energy reserve. When the electrical energy supply is an alternative supply (in English Alternative Current AC), a simple comparison of a voltage delivered by a peak detector to a threshold does not make it possible to obtain a detection in a duration of less than a half power supply period.

SUMMARY OF THE INVENTION The aim of the present invention is to solve the drawbacks of the prior art by proposing a device for detecting a drop in voltage of the electric power supply which makes it possible to detect, within a period less than half an alternation of the electrical supply, a total loss of the alternative electrical supply or a drop in the value of the voltage of the alternative electrical supply.

To this end, according to a first aspect, the invention provides a device for detecting a drop in voltage of an alternative power supply delivering electrical energy to an energy converter in order to power electrical equipment. , the device being connected to a reserve of electrical energy for supplying the energy converter, characterized in that the device comprises:

- a full-wave rectifier for rectifying the alternating power supply, - a comparator which compares a first predetermined voltage with a full-wave rectified voltage obtained from a full-wave rectifier which rectifies the alternating power supply, [0012] a capacitor charging circuit for charging the capacitor when the rectified voltage is below the predetermined threshold, a capacitor discharge circuit for discharging the capacitor when the rectified voltage is above the predetermined threshold, [0014] - A comparator to compare the voltage across the capacitor with a second predetermined voltage, - a control circuit of the electrical energy reserve to activate the electrical energy reserve for the supply of electrical energy to the converter d energy only when the voltage across the capacitor is greater than the second te predetermined nsion.

Thus, it is possible to detect, within less than half a half of the power supply, a total loss of the alternative power supply or a drop in the value of the voltage of the power supply alternative.

In addition, the device for detecting a voltage drop in an AC power supply has few electronic components and thus has a reduced footprint which facilitates its use in an aircraft.

The charging circuit of a capacitor for charging the capacitor when the rectified voltage is less than the predetermined threshold constitutes a time delay, the value of which is determined according to the characteristics of the alternating supply and of the energy converter.

According to a particular embodiment of the invention, the device comprises means for shifting the full-wave rectified voltage in voltage when the voltage across the capacitor is greater than the second predetermined voltage.

Thus, the detection of a drop in voltage or a total loss of the power supply is possible within less than half a half of the power supply while avoiding false detection.

According to a particular embodiment of the invention, the device comprises means for shifting the voltage of the second predetermined voltage when the first predetermined voltage is greater than the full-wave rectified voltage.

Thus, the detection is straightforward and stable and is robust to untimely detections linked to parasitic voltages which would add to the measured voltage.

According to a particular embodiment of the invention, the device comprises means for shifting the full-wave rectified voltage in voltage when the voltage across the capacitor is greater than the second predetermined voltage.

Thus, the detection is insensitive to an increase in the level of the voltage of the power supply during variations in the consumption of electrical energy, increase for example linked to a drop in line voltage losses.

According to a particular embodiment of the invention, the device comprises means for notifying the electrical equipment when the reserve of electrical energy is ordered activated for the supply of electrical energy to the energy converter only when the voltage across the capacitor is greater than the second predetermined voltage.

Thus, the electrical equipment can perform operations such as for example storing data or stopping a computer program before the reserve of electrical energy is exhausted.

The invention also relates to an aircraft characterized in that it comprises the device for detecting a drop in voltage of an alternative power supply delivering electrical energy to the energy converter according to the present invention.

Brief Description of the Drawings The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the drawings seals, among which:

[Fig.l] shows a system for detecting a drop in voltage of an alternative power supply delivering electrical energy to an energy converter in order to power electrical equipment in which the present invention is implemented ;

[Fig.2] shows an example of the evolution of an alternative power supply and the detection of a voltage drop of an alternative power supply delivering electrical energy to an energy converter in order to power electrical equipment;

[Fig.3] is a block diagram of a module for detecting a drop in voltage of the electric power supply according to the present invention;

[Fig.4] is an example of an electrical diagram of a device for detecting a drop in voltage of the electric power supply according to the present invention;

[Fig.5] shows the evolution of different signals in the module for detecting a drop in voltage of the electric power supply according to the present invention;

[Fig.6] shows the evolution of different signals in the module for detecting a drop in voltage of the electric power supply when a total loss of the AC supply appears and when the supply in electrical energy returns to a nominal operating range;

[Fig.7] shows the evolution of different signals in the module for detecting a drop in voltage of the electric power supply when a progressive drop in the AC supply appears and when the supply in electrical energy returns to a nominal operating range.

DETAILED PRESENTATION OF EMBODIMENTS [0037] FIG. 1 shows a system for detecting a drop in voltage of an alternative supply supplying electrical energy to an energy converter in order to supply electrical equipment in which the present invention is implemented.

The system for detecting a drop in voltage of an alternative power supply delivering electrical energy supplied by a bus 110 comprises an energy converter 130 which supplies one or a plurality of electrical devices such as cards electronic 140a, 140b and 140c.

Electrical equipment can for example be an electric motor.

The system for detecting a drop in voltage of an AC power supply includes a reserve of electrical energy 120 which is activated by a detection module 100 according to the present invention.

When the electrical equipment is electronic cards, the detection module 100 according to the present invention can be connected to electronic cards 140a to 140c so as to inform them of the loss of alternative electrical energy, for example to perform a saving of treatments in progress.

The system is in a particular mode of the present invention on board an aircraft.

[0043] FIG. 2 shows an example of the evolution of an alternative power supply and the detection of a drop in voltage of an alternative power supply delivering electrical energy to an energy converter in order to power electrical equipment.

The voltage of the electric power supply from bus 110 is denoted 200.

The signal at the output of the detection module 100 is denoted 220 in Lig. 2.

When the electrical power supply to the bus 110 is broken, the detection module 100 detects it during the period TA.

When the voltage of the electric power supply to the bus 110 becomes lower than an operating threshold of the energy converter 130, the detection module 100 detects it during the duration TB.

The Lig. 3 is a block diagram of a module for detecting a voltage drop in the electrical energy supply according to the present invention.

The voltage drop detection module of the electric power supply 100 includes a full wave rectification device 310 which supplies a rectified IN signal to the voltage drop detection device of the power supply in electrical energy 300.

The Lig. 4 is an example of an electrical diagram of a device for detecting a drop in voltage of the electrical energy supply according to the present invention.

The input IN of the device for detecting a drop in voltage of the electric power supply is connected to a first termination of a resistor R400. A second termination of the resistor R400 is connected to a first termination of a resistor R401, the anode of a Zener diode D43, to a first termination of a capacitor C40 and to a positive input of a comparator U40.

A second termination of the resistor R401 is connected to the ground of a continuous supply Vcc.

A second termination of the capacitor C40 is connected to ground.

The resistors R400 and R401 form a voltage divider bridge of the rectified alternating voltage present on the input IN.

A cathode of a diode D42 is connected to an anode of a diode D41 and to the positive input of the comparator U40.

The anode of diode D42 is connected to ground and the cathode of diode D41 is connected to the supply Vcc. The function of diodes D41 and D42 is to protect the input of the comparator U40.

When the input of the comparator U40 does not need to be protected, the diodes D41 and D42 can be deleted.

A first termination of a resistor R402 is connected to a voltage reference Vref, the value of which is for example 2.048V and to a cathode of a diode D40.

A second termination of the resistor R402 is connected to a first termination of a capacitor C42, to the anode of the diode D40 and to a negative input of the comparator U40.

A second termination of the capacitor C42 is connected to ground.

This device makes it possible to avoid inadvertent trips when the system is powered up when the internal supply voltages of the detection device have not yet stabilized.

The voltage reference Vref, the resistor R402, the capacitor C42 and the diode D40 give a constant voltage on the negative input of the comparator U40.

The kind of comparator U40 is connected to the gate of a transistor T40, to a first termination of a resistor R403 and to a first termination of a resistor R404.

A second termination of the resistor R403 is connected to the cathode of the Zener diode D43 and a second termination of the resistor R404 is connected to the supply Vcc which supplies the comparator U40.

When the voltage on the positive input at the input of the comparator U40 is greater than the voltage on the negative input of the comparator U40, the output of the comparator U40 is at the high level and saturates the transistor T40.

When the voltage on the positive input at the input of the comparator U40 is less than the voltage on the negative input of the comparator U40, the output of the comparator U40 is at low level, blocks the transistor T40.

A hysteresis voltage then appears on the positive input of the comparator U40.

The resistors R403, R404 and the diode D43 form the hysteresis voltage.

The source of transistor T40 is connected to ground and the drain of transistor T40 is connected to a first termination of a resistor R405.

A second termination of the resistor R405 is connected to a first termination of a capacitor C43, to a first termination of a resistor R406 and to a negative input of a comparator U41.

A second termination of the resistor R406 is connected to the Vcc supply which supplies the comparator UR41.

A second termination of the capacitor C43 is connected to ground.

A first termination of a resistor R408 is connected to the voltage reference Vref and to a cathode of a diode D44.

The voltage reference is for example 2.048V, it could be quite different in another application, with an adaptation of the time constant from R405 and C43.

A second termination of the resistor R408 is connected to a first termination of a capacitor C44, to the anode of the diode D44, to a first termination of a resistor R407 and to a negative input of the comparator U40.

A second termination of the capacitor C44 is connected to ground.

The voltage reference Vref, the resistor R408, the capacitor C44 and the diode

D44 give a constant voltage on the positive input of comparator U41.

A second termination of the resistor R407 is connected to the anode of a diode D45 whose cathode is connected to the output of the comparator U41.

When the transistor T40 conducts, the capacitor C43 is discharged via the resistor R405 of low value.

When the transistor T40 is blocked, the capacitor C43 is charged via the resistor R406.

When the voltage across the capacitor C43 is less than the voltage on the positive input of the comparator U41, the output of the comparator U41 is in the high state.

When the voltage across the capacitor C43 is greater than the voltage on the positive input of the comparator U41, the output of the comparator U41 is in the low state, the diode D45 conducts and a hysteresis appears on the positive input of comparator U41.

This very high hysteresis makes it possible to lock the switching of the output of the comparator U41, the triggering of which was caused by exceeding the time delay defined by R406 and C43.

The output of comparator U41 is connected to the output OUT of the device for detecting a drop in voltage of the electric power supply and to a first termination of a resistor R409. A second termination of resistor R409 is connected to a cathode of a diode D46.

The anode of diode D46 is connected to the positive input of the comparator U40.

The resistor R409 and the diode D46 form a hysteresis when the output of the comparator U41 is in the low state.

The hysteresis thus produced makes it possible to lock the entire chain for detecting a drop in the supply voltage of electrical energy as soon as the event occurs.

Unlocking occurs when the input voltage IN returns to the normal operating range, that is to say by applying a voltage to the input plus of the comparator U40 beyond the hysteresis created by R409. and D46.

The Lig. 5 shows the evolution of different signals in the module for detecting a voltage drop in the electrical energy supply according to the present invention.

In Lig. 5, the voltage Vbus is shown, the voltage IN at the input of the device for detecting a drop in voltage of the electric power supply, the voltage OUT at the output of the device for detecting a drop in voltage in the supply in electrical energy and the voltage VU41- present on the negative input of the comparator U41.

At time 50a, the voltage IN is greater than the minimum operating value of the energy converter 130, the transistor T40 of the Lig. 4 is saturated and the capacitor C43 is discharged. The OUT output is high and the energy reserve is not activated.

At time 52a, the voltage IN is less than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is blocked and the capacitor C43 charges until time 50b and the value at the negative input of the comparator U41 is less than the voltage on the positive input of the comparator UR1, the output OUT remains in the high state and the energy reserve is not activated.

At time 50b, the voltage IN is greater than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is saturated and the capacitor C43 discharges, the value at the negative input of the comparator U41 is less than the voltage on the positive input of the comparator UR1, the output OUT remains high and the energy reserve n 'is not activated.

At time 52b, the voltage IN is less than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is blocked and the capacitor C43 charges up to the instant 50c and the value at the negative input of the comparator U41 is less than the voltage on the positive input of the comparator UR1, the output OUT remains in the high state and the energy reserve is not activated.

At time 50c, the voltage IN is greater than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is saturated and the capacitor C43 discharges, the value at the negative input of the comparator U41 is less than the voltage on the positive input of the comparator UR1, the output OUT remains high and the energy reserve n 'is not activated.

At time 52c, the voltage IN is lower than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is blocked and the capacitor C43 charges until time 54a and the value at the negative input of the comparator U41 is greater than the voltage on the positive input of the comparator UR1, the output OUT goes to the low state and the energy reserve is activated.

At time 50d, the voltage IN is greater than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is saturated and the capacitor C43 discharges, the value at the negative input of the comparator U41 is less than the voltage on the positive input of the comparator UR1, the output OUT remains high and the energy reserve n 'is not activated.

At time 52d, the voltage IN is less than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is blocked and the capacitor C43 charges up to the instant 50e and the value at the negative input of the comparator U41 is less than the voltage on the positive input of the comparator UR1, the output OUT remains in the high state and the energy reserve is not activated.

At time 50e, the voltage IN is greater than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is saturated and the capacitor C43 discharges, the value at the negative input of the comparator U41 is lower than the voltage on the positive input of the comparator UR1, the output OUT remains high and the energy reserve is not activated.

At time 52e, the voltage IN is less than the minimum operating value of the energy converter 130, the transistor T40 in FIG. 4 is blocked and the capacitor C43 charges until time 54b and the value at the negative input of comparator U41 is greater than the voltage on the positive input of comparator UR1, the output OUT goes low and the energy reserve is activated.

[0101] FIG. 6 shows the evolution of different signals in the module for detecting a drop in voltage of the electrical power supply when a total loss of the alternative power supply appears and when the electrical power supply returns within a range of nominal operation.

In FIG. 6, the voltage IN at the input of the device for detecting a voltage drop in the supply of electrical energy is shown, the voltage OUT at the output of the device for detecting a drop in voltage in the supply of electrical energy, the voltage VU40- on the negative input of the comparator U40, the voltage VU40 + on the negative positive input of the comparator U40, the voltage SU40 at the output of the comparator U40 and the voltage VU41- present on the negative input of the comparator U41.

The hysteresis 60 is caused by the conduction of the diode D43.

The hysteresis 61 is caused by the conduction of diodes D45 and D46.

[0105] FIG. 7 shows the evolution of different signals in the module for detecting a drop in voltage of the electrical power supply when a gradual drop in the alternative power supply appears and when the electrical power supply returns within a range of nominal operation.

[0106] In FIG. 7, the voltage IN at the input of the device for detecting a voltage drop in the supply of electrical energy is shown, the voltage OUT at the output of the device for detecting a drop in voltage in the supply of electrical energy, the voltage VU40- on the negative input of the comparator U40, the voltage VU40 + on the negative positive input of the comparator U40, the voltage SU40 at the output of the comparator U40 and the voltage VU41- present on the negative input of the comparator U41.

During the period noted 70, the voltage on the positive input at the input of the comparator U40 is greater than the voltage on the negative input of the comparator U40, the output of the comparator U40 is at the high level and saturates the transistor T40 and a hysteresis voltage appears on the positive input of comparator U40.

During the period noted 71, the voltage on the positive input at the input of the comparator U40 is less than the voltage on the negative input of the comparator U40, the output of the comparator U40 is at low level, blocks the transistor T40.

[0109]

During the period noted 72, the voltage across the capacitor C43 is greater than the voltage on the positive input of the comparator U41, the output of the comparator U41 is in the low state, the diode D45 conducts and a hysteresis appears on the positive input of comparator U41; diode D46 also leads and a hysteresis 80 appears on the entire detection chain.

Claims (5)

1. Device for detecting (100) a voltage drop of an alternative power supply (110) delivering electrical energy to an energy converter (130) in order to supply electrical equipment (140a, 140b, 140c ), the device (100) being connected to a reserve of electrical energy (120) for supplying the energy converter, characterized in that the device (100) comprises: - a full wave rectifier to rectify the alternating power supply, - a comparator which compares a first predetermined voltage to a full-wave rectified voltage obtained from the full-wave rectifier which rectifies the alternating supply, - a capacitor charging circuit for charging the capacitor when the rectified voltage is lower than the first predetermined voltage, a capacitor discharge circuit for discharging the capacitor when the rectified voltage is greater than the first predetermined voltage, - a comparator to compare the voltage across the capacitor with a second predetermined voltage, - a control circuit of the electrical energy reserve to activate the electrical energy reserve for the supply of electrical energy to the energy converter only when the voltage across the capacitor is greater than the second predetermined voltage. 2. Device according to claim 1, characterized in that the device (100) comprises means for shifting the full-wave rectified voltage in voltage when the voltage across the capacitor is greater than the second predetermined voltage. 3. Device according to claim 2, characterized in that the device (100) comprises means for shifting the voltage of the second predetermined voltage when the first predetermined voltage is greater than the full-wave rectified voltage. 4. Device according to any one of claims 1 to 3, characterized in that the device (100) comprises means for notifying the electrical equipment when the reserve of electrical energy is ordered activated for the supply of electrical energy of the energy converter only when the voltage across the capacitor is greater than the second predetermined voltage. 5. An aircraft characterized in that it comprises the device (100) for detecting a drop in voltage of an alternative supply supplying electrical energy to the energy converter according to any one of claims 1 to 4.